It's that time of year again and I = haven't even yet finished installed the front AC in my Syncro Westy.  Time to think = of HEAT!.
 
I have researched this = topic also for the last two winters.   Here's what I'm currently = considering.  There are a couple of European gas furnaces (Propex and Truma) but they are = extremely expensive and hard to get and they don't seem to put out enough heat for = really cold climates.
 
There are two small vented propane RV = furnaces made in the US that seem a good fit  (size wise) into a vanagon and = they are available from 12,0000 -20000 BTU sizes which should heat a Vanagon = quite well.  .  I have seen a couple of them installed.
 
One is made by Atwood (aka = Hydro-Flame).  Model is called the "Everest Star".  The sell new for around $425 = but you can get one from an RV salvage yard for $200-$250.  TIK I think one = could be fitted nicely into the little square cabinet area close to the = floor, to the left of the Westy fridge.
 
The other compact furnace is made by = Suburban which is well known in the RV world and they also make the furnace that is = currently used in the Eurovan Camper.  I owned one of these campers for a = while and the furnace was the nicest feature of the van. 
Suburban makes a model called the "NT" = series which is very compact---only about 9.5" square.   Seems like it = would also fit in the same location mentioned above for the Hydro-Flame.  = Prices for these are about the same reatial, but there's a dealer that sells them = on eBay for about $325.
 
Both models can be controlled by a thermostat,---just like at home.  Wonderful on cold mornings or = arriving to a cold campground late at night.  Just turn the switch, set your = temp and forget it.   You may need an extra propane tank for long = camping trips though.
 
Both of these heaters must be installed = perpendicular to the outer wall of the van and therefore somewhere on = the cabinet side.  The vent pipe must go straight to the outside of the = van with no bends.  They cannot be mounted under the seat like the = European heaters with a vent that bends 90 degrees to reach the outside wall of = the van.
 
Here's a useful link with pictures and = sizes for both furnaces:
 
http://www.marksrv.com/furnac= e.htm
 
I have not yet installed either of = them, but I have seen the Atwood (Hydro-Flame) model installed in a couple of Country = Homes (non Westy) camper conversions.